[Gate-users] Energy deposited by Compton interaction

[Chen, Yu]

Hi, Anayisse,

Do you have a specific purpose needed to study from hits?

To start from hits data file, you really need a clear idea what the hits are about and
how they are recorded. I suggest you reading Geant4 manual about step function and GATE manual about hit
carefully.

See below for specific answer for your question.

Yu Chen, Ph.D.
University of Massachusetts Medical School
Division of Nuclear Medicine
55 Lake Avenue North
Worcester, MA 01655-0243
Phone:  (508) 856-6123
Fax:    (508) 856-4572



-----Original Message-----
From: gate-users-bounces at lists.healthgrid.org on behalf of anayisse arnaud
Sent: Fri 12/21/2007 11:43 AM
To: gate-users at lists.healthgrid.org
Subject: [Gate-users] Energy deposited by Compton interaction
 


Dear Gate users,

I hope you can help me explain these results : I have always the energy deposited by Compton interaction = 0 , it's impossible .... !! 
can you help me understand why ?

A: Yes, it is possible. It indeed is designed in Geant4 to have one step (hit) for each Compton scattering process no matter whether the 
required step length is longer than input parameter of interaction range. In this step, a scattered electron is generated and the initial
photon momentum is recalculated. Therefore no energy is deposited in this step. Energy deposits are by following scattered electron through 
ioning (eIoni) and multiple scattering (msc) processes, and by scattered photon through photoelectric (phot) process. Of course, the scattered photon
can occur another compton process as indicated by your gateHits.dat below.

Can you tell how those two photons from your primary source transport from your gateHits.dat?

-Yu



Here some lines from the gateHits.dat file after a very simple PET scanner simulation :

       0       4   2   0     0    98     0     0     0     0   4.80830738641700296894139e-05  0.000e+00  5.900e+00  5.387e+00 -6.378e+01 -8.914e+00      22     2     0   1    0    0 compt NULL NULL
       0       4   2   0     0    98     0     0     0     0   4.80830738648918237332190e-05  2.890e-03  1.164e-04  5.387e+00 -6.378e+01 -8.914e+00      11     3     2   1    0    0 eIoni NULL NULL
       0       4   1   0     0   930     0     0     0     0   4.80830725456377712154210e-05  0.000e+00  5.505e+00 -5.354e+00  6.339e+01  8.859e+00      22     1     0   2    0    0 compt NULL NULL
       0       4   1   0     0   930     0     0     0     0   4.80830725460870645956990e-05  1.033e-02  8.112e-04 -5.354e+00  6.339e+01  8.859e+00      11     4     1   2    0    0 eIoni NULL NULL
       0      15   2   0     0   509     0     0     0     0   1.75863105737611002260534e-04  0.000e+00  5.199e+00  5.937e+01 -9.981e+00 -2.245e+00      22     2     0   1    0    0 compt NULL NULL
       0      15   2   0     0   637     0     0     0     0   1.75863124194323804235993e-04  5.024e-02  1.904e+00  5.555e+01 -7.918e+00  1.178e+00      22     2     0   1    0    0 phot NULL NULL
       0      15   2   0     0   637     0     0     0     0   1.75863124237332288379854e-04  1.345e-01  5.869e-02  5.554e+01 -7.914e+00  1.184e+00      11     4     2   1    0    0 eIoni NULL NULL
       0      15   2   0     0   509     0     0     0     0   1.75863105817652010803842e-04  6.486e-02  3.775e-02  5.940e+01 -9.974e+00 -2.234e+00      11     3     2   1    0    0 msc NULL NULL
       0      15   2   0     0   509     0     0     0     0   1.75863105916834852647870e-04  2.614e-01  1.659e-01  5.941e+01 -9.980e+00 -2.217e+00      11     3     2   1    0    0 eIoni NULL NULL
       0      23   2   0     0   244     0     0     0     0   2.79542904503920954916579e-04  0.000e+00  1.361e+00  4.617e+01 -3.233e+01 -5.875e+00      22     2     0   1    0    0 compt NULL NULL
       0      23   2   0     0   374     0     0     0     0   2.79542924092678708378190e-04  5.024e-02  1.776e-01  5.034e+01 -2.825e+01 -5.234e+00      22     2     0   1    0    0 phot NULL NULL
       0      23   2   0     0   374     0     0     0     0   2.79542924143725331903587e-04  2.290e-01  1.359e-01  5.035e+01 -2.824e+01 -5.231e+00      11     4     2   1    0    0 eIoni NULL NULL



Thank you very much

Anayisse
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